JP2000065526A - Method and device for position detection, manufacture of aberration correcting member, and projection optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect the position of an optical member of the projection optical device. SOLUTION: The positions of two images formed on an observation surface 79S by irradiating a 1st mark FZP1 formed on a reference member R for position detection and a 2nd mark FZP2 formed on an optical member 16D as an object of position detection with lights are measured. According to the positional relation between the two images on the observation surface 79S, the positional relational between the reference member R and optical member 16D is precisely detected. A high-performance optical member and a projection optical device which has precise image formation characteristics can be manufactured by detecting the position detection mentioned above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting method, a position detecting device, a method of manufacturing an aberration correcting member, and a projection optical device. Detection method for detecting the position of an optical member arranged on the optical path of illumination light in a projection optical device for projecting the pattern, a position detection device using the position detection method, and aberration correction using the position detection method The present invention relates to a method of manufacturing a member and a projection optical device including the aberration correction member.

[0002]

2. Description of the Related Art Conventionally, in a lithography process for manufacturing a semiconductor device, a liquid crystal display device, or the like, a pattern formed on a mask or a reticle (hereinafter, collectively referred to as a “reticle”) is resisted through a projection optical system. There is used an exposure apparatus that transfers a wafer onto a substrate such as a wafer or a glass plate (hereinafter, referred to as a “sensitive substrate or wafer” as appropriate). As this type of apparatus, a step-and-repeat type reduction projection exposure apparatus (so-called “stepper”) and a step-and-scan type scanning exposure apparatus are known.

In such an exposure apparatus, a projection optical system is used to project a pattern formed on a reticle onto a wafer. Such a projection optical system is configured, for example, by combining lens elements, but aberrations occur according to the adjustment accuracy of the projection optical system. Further, no matter how the adjustment accuracy is improved, there is a limit in the homogeneity of materials of the components of the projection optical system and the processing accuracy, and random aberration is inevitably generated.

In order to correct aberrations caused by the projection optical system, a technique of arranging an aberration correction plate on an optical path of illumination light applied to the reticle from the reticle to the wafer, for example, between the reticle and the projection optical system has been proposed. JP-A-9-9260
No. 1 discloses this. Such an aberration correction plate is, for example, a flat glass plate as a starting material, and the starting material is mechanically positioned and arranged with reference to, for example, a positioning member provided on a lens barrel of a projection optical system, and then the wafer is mounted on a wafer. It has been manufactured by measuring the aberration of the projected image and processing the starting material removed from between the reticle and the projection optical system based on the arrangement position of the starting material and the measurement result of the aberration at the time of measuring the aberration.

[0005]

The accuracy of aberration correction by the above-described aberration correction plate is determined by the accuracy of the arrangement position of the starting material and the accuracy of the aberration measurement result when measuring the aberration. Here, since the aberration measurement accuracy generally uses an optical measurement system, it is determined by the optical accuracy of the measurement system. On the other hand, in the above-described prior art, since the positioning of the starting material at the time of measuring the aberration is mechanically performed, the accuracy of the arrangement position of the starting material at the time of measuring the aberration is determined by the mechanical positioning accuracy of the positioning member. On the other hand, with the miniaturization of semiconductor elements, improvement in exposure accuracy is required, but it is clear that conventional aberration correction accuracy will not be able to satisfy the demand for improvement in exposure accuracy in the near future. I have.

The present invention has been made under such circumstances, and a first object of the present invention is to provide a position detection method and a position detection device capable of improving the position detection accuracy.

A second object of the present invention is to provide a method of manufacturing an aberration correcting member capable of correcting the aberration of a projection optical system with high accuracy.

A third object of the present invention is to provide a projection optical apparatus for projecting a pattern formed on a first object onto a second object with high accuracy.

[0009]

According to the position detecting method of the present invention, a first object (R) is irradiated with illumination light, and a pattern formed on the first object (R) is projected onto a projection optical system (PL). In a position detecting method for detecting a position of an optical member (16D) arranged on an optical path of the illumination light in a projection optical device for projecting the second object (W) via the first object (R) and the first object (R), A relative position of the optical member (16D) with respect to at least one of the lens barrels of the projection optical system (PL) is optically detected.

According to this, the first object (R) of the optical member arranged on the optical path of the illumination light and the projection optical system (P)
Since the relative position to at least one of the lens barrels L) is optically detected, accurate position detection is possible. By positioning the optical member based on the result of the position detection, for example, The accuracy of the optical member can be improved by about one digit or more as compared with the case of performing the alignment. Note that the optical member can be an optical member for measuring aberration, or an optical member to be processed for aberration correction.

In the position detecting method according to the present invention, the optical position is detected, for example, by inspecting light via at least one first mark formed on at least one of the first object and the lens barrel of the projection optical system. Is a positional relationship between a first inspection image formed on the observation surface and a second inspection image formed on the observation surface by inspection light via at least one second mark formed on the optical member. This can be performed by detecting a relative position of the optical member with respect to at least one of the first object and the lens barrel of the projection optical system.

In such a case, the first mark and the second mark can be Fresnel zone plates. According to this, the first mark and the second mark are formed as Fresnel zone plates having an image forming ability, so that the first inspection image and the second inspection image can be formed on the observation surface without using a special image forming optical system. An inspection image can be formed. Therefore, the position of the optical member can be detected with a simple configuration.

The position detecting device of the present invention irradiates the first object (R) with illumination light, and converts the pattern formed on the first object (R) through the projection optical system (PL) to the second object (R). (W)
A position detecting device for detecting a position of an optical member (16D) arranged on an optical path of the illumination light in a projection optical device for projecting the first object (R) and the projection optical system (PL). A light source that generates inspection light that illuminates at least one first mark (FZP1) formed on at least one of the lens barrels and at least one second mark (FZP2) formed on the optical member (16D). 7
1); a first inspection image (IM1) formed on the observation surface (79S) by light passing through the first mark (FZP1) and light passing through the second mark (FZP2) pass through the observation surface (79). 7
9S) The optical member (16D) for at least one of the first object (R) and the lens barrel of the projection optical system (PL) based on the positional relationship with the second inspection image (IM2) formed on the second inspection image (IM2). And a processing device (26) for detecting the relative position of.

According to this, the light output from the light source is
A first inspection image is formed on the observation surface via the first mark, and a second inspection image is formed on the observation surface via the second mark. Then, the processing device detects the position of the optical member based on the positional relationship between the first inspection image and the second inspection image on the observation surface. That is, the position detecting device of the present invention detects the position of the optical member by using the position detecting method of the present invention. Therefore, the position of the optical member can be accurately detected.

According to the method of manufacturing an aberration correcting member of the present invention, the first object (R) is irradiated with illumination light, and the pattern formed on the first object (R) is projected via a projection optical system (PL). Second
A method of manufacturing an aberration correction member used in a projection optical device that projects onto an object (W), wherein an optical member (16D) is disposed on an optical path of the illumination light, and the first object (R) and the Optically detecting the relative position of the optical member (16D) to at least one of the lens barrels of the projection optical system (PL);
A first step of aligning the optical member (16D) with at least one of the first object (R) and a lens barrel of the projection optical system (PL) based on the detection result; A second step of measuring the aberration of the projected image on the second object (W) in a state where the optical member (16D) is aligned; and, based on the measurement result in the second step, the optical member ( 16D) or an optical member that is substantially the same as the optical member described above, and the aberration correction member (1
6) the third step of manufacturing.

According to this, on the optical path of the illumination light from the first object to the second object, the optical member is positioned and arranged with respect to at least one of the first object and the lens barrel of the projection optical system, Perform aberration measurement. Here, the positioning of the optical member is performed based on a detection result obtained by detecting the relative position of the optical member arranged on the optical path of the illumination light with respect to the first object by the position detection method of the present invention. The member and the first object or the barrel of the projection optical system are accurately positioned. As a result, the relationship between the measured aberration and the position of the optical member can be accurately determined. Then, based on the aberration measurement result, the optical member or an optical member substantially the same as the optical member is processed to manufacture an aberration correction member. Therefore, it is possible to manufacture an aberration correction member that corrects aberration with high accuracy.

Here, if another optical member substantially identical to the optical member is to be processed, it is not necessary to remove the optical member from the optical path of the illumination light. Therefore,
The assembly and adjustment of the projection optical device which can be performed in a state where the optical member is arranged on the optical path of the illumination light, that is, in a state where a small aberration remains due to the projection optical system, is processed from another optical member to an aberration correction member. While you can continue.

The projection optical device according to the present invention is a projection optical device for irradiating a first object (R) with illumination light and projecting a pattern formed on the first object (R) onto a second object (W). The aberration correcting member (1) disposed on the optical path of the illumination light and manufactured by the method for manufacturing an aberration correcting member of the present invention.
6) and; the illumination light through the first object (R) is incident;
A projection optical system (PL) for projecting the pattern on the second object (W).

According to this, since the accurate aberration correcting member manufactured by the method for manufacturing the aberration correcting member of the present invention is provided, the aberration of the projected image projected on the second object can be reduced. The pattern formed on one object can be accurately projected on the second object.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection exposure apparatus as a projection optical apparatus according to an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 schematically shows the configuration of a projection exposure apparatus 100 according to one embodiment. This projection exposure apparatus 100 synchronously moves a reticle R as a first object and a wafer W as a second object, and transfers a pattern formed on the reticle R via a projection optical system PL as an imaging optical system. This is a scanning type exposure apparatus that transfers the image onto a shot area of a wafer W.

The projection exposure apparatus 100 includes an illumination system 10 including a light source and a reticle stage R for holding a reticle R.
S, an aberration correcting plate 16 as an aberration correcting member for correcting aberration of the projection optical system PL, a projection optical system PL for projecting an image of a pattern formed on the reticle R onto the wafer W, and a wafer W
And a control system and the like.

The illumination system 10 includes an illuminance uniforming optical system including a light source and a fly-eye lens, a relay lens, a variable N
It is configured to include a D filter, a reticle blind, a dichroic mirror, and the like (all not shown).
The configuration of such an illumination system is disclosed in, for example, Japanese Patent Application Laid-Open No. 10-112.
No. 433. In this lighting system 10,
A slit-shaped illumination area portion IAR defined by a reticle blind on a reticle R on which a circuit pattern or the like is drawn
(See FIG. 2) is illuminated with substantially uniform illuminance by the illumination light IL.

A reticle R is fixed on the reticle stage RS by, for example, vacuum suction. Here, the reticle stage RS is driven by an optical axis of an illumination optical system (an optical axis of a projection optical system PL described later) for positioning the reticle R by a reticle stage driving unit (not shown) composed of a magnetic levitation type two-dimensional linear actuator. It can be driven minutely in an XY plane perpendicular to AX) and can be driven at a scanning speed designated in a predetermined scanning direction (here, Y direction). Further, in the present embodiment, the magnetic levitation type two-dimensional linear actuator includes a Z drive coil in addition to the X drive coil and the Y drive coil, and thus can be minutely driven in the Z direction.

The position of the reticle stage RS in the stage movement plane is determined by a reticle laser interferometer (not shown; hereinafter, referred to as a "reticle interferometer") and a movable mirror (not shown).
, Is always detected at a resolution of, for example, about 0.5 to 1 nm. Reticle stage RS from reticle interferometer
Is sent to the stage control system 58, and the stage control system 58 drives the reticle stage RS via a reticle stage driving unit (not shown) based on the position information of the reticle stage RS.

The projection optical system PL is arranged below the reticle stage RS in FIG. 1, and the direction of the optical axis AX is the Z-axis direction. In this case, the optical axis AX direction is set so that the optical arrangement is telecentric on both sides. , A plurality of lens elements 40a, 40b,
.. Are used. The projection optical system PL has a predetermined projection magnification, for example, 1/5 (or 1
/ 4). Therefore, the lighting system 1
Illumination area IA of reticle R by illumination light IL from 0
When R (see FIG. 2) is illuminated, a reduced image (partially inverted image) of the circuit pattern of the reticle R in the illumination area IAR via the projection optical system PL is generated by the illumination light IL passing through the reticle R. It is formed on a wafer W having a surface coated with a photoresist.

Of the lens elements, the uppermost lens element 40a closest to the reticle stage RS
Is held by a ring-shaped support member 42, which can be extended and retracted by a driving element such as a piezo element 4.
4a, 44b, and 44c (the drive element 44c on the back side of the drawing is not shown), and is supported at three points and a lens barrel 46 is provided.
Is linked to Similarly, the second lens element 40b from the top is held by a ring-shaped support member 43. This support member 43 is a telescopic drive element, for example, piezo elements 45a, 45b, 45c (a drive element on the back side of the drawing). 45c is not shown) and is supported at three points and connected to the lens barrel 46.

By the driving elements 44a, 44b, and 44c, three points around the lens element 40a are independently set.
It can be moved in the direction of the optical axis AX of the projection optical system PL, and three points around the lens element 40b can be independently moved in the direction of the optical axis AX of the projection optical system PL by the driving elements 45a, 45b, and 45c. Is available. Then, these drive elements 44a, 4a
The voltages applied to 4b, 44c and 45a, 45b, 45c are controlled by the imaging characteristic correction controller 47 based on a command from the main controller 26, whereby the driving elements 44a, 44b, 44c and 45a, 45b,
45c is controlled. In addition,
In FIG. 1, the optical axis AX of the projection optical system PL coincides with the optical axis of a lens element (lens elements (not shown) other than 40a and 40b) fixed to the lens barrel 46.

Further, in this embodiment, a sealing chamber 49 is formed between specific lens elements near the center of the projection optical system PL in the optical axis direction, and the sealing chamber 49 is formed.
Is adjusted by a pressure adjusting mechanism (for example, a bellows pump or the like) 48. The pressure adjusting mechanism 48 is also controlled by the imaging characteristic correction controller 47 based on a command from the main controller 26, and thereby adjusts the internal pressure of the sealed chamber 49.

In this embodiment, the lens element 40a
And 40b are adjusted, for example, by adjusting the projection magnification, the field curvature, and the symmetric distortion component by moving or tilting the optical axis AX, and by adjusting the internal pressure of the sealed chamber 49, for example, adjusting the magnification, coma aberration, and field curvature. Is performed.

A wafer holder 52 is mounted on the wafer stage 50, and a wafer W as a sensitive substrate is held by the wafer holder 52 by vacuum suction. The wafer stage 50 is mounted on the wafer W
In the X, Y, and Z directions.

A movable mirror 53 for reflecting a laser beam from a wafer laser interferometer (hereinafter, referred to as a "wafer interferometer") 56 is fixed on the wafer stage 50, and is provided by a wafer interferometer 56 disposed outside. XY of wafer W
The position in the plane is always detected with a resolution of, for example, about 0.5 to 1 nm. Here, the position information (or speed information) of the wafer W is sent to the main controller 26, and the stage control system 58 drives the wafer based on the position information (or speed information) in response to an instruction from the main controller 20. The wafer stage 50 is moved to the XY direction through an apparatus 54 (this includes all driving systems in each of the X direction, the Y direction, and the Z direction).
Drive control in the plane.

On the wafer stage 50, a fiducial mark plate FM whose surface is the same as the surface of the wafer W is fixed. On the surface of the fiducial mark plate FM, a first fiducial mark to be measured by the wafer alignment microscope 35 is formed at the center in the longitudinal direction, as disclosed in, for example, JP-A-10-163099. A pair of second reference marks used for relative position measurement with respect to the reticle R are formed on both sides in the longitudinal direction of the reference mark through the projection optical system PL.

Further, the apparatus shown in FIG. 1 has an oblique incident light type focus detection for detecting the position in the Z direction (optical axis AX direction) of the portion in the exposure area IA on the surface of the wafer W and the area in the vicinity thereof. A multipoint focus position detection system, which is one of the systems (focus detection system), is provided. As shown in FIG. 1, this multipoint focus position detection system includes an irradiation optical system 60a.
And a light receiving optical system 60b. The detailed configuration of the multi-point focus position detection system is disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 6-283403.

In the apparatus shown in FIG. 1, an image of a pair of second fiducial marks on the fiducial mark plate FM via the projection optical system PL and a reticle alignment mark on the reticle R are provided above the reticle R. Reticle alignment microscope unit 30A and a reticle alignment microscope unit 30B (not shown) for observing (omitted) at the same time. The detection signals of these reticle alignment microscope units 30A and 30B are supplied to main controller 26. Further, when the exposure sequence is started, reticle alignment microscope units 30A and 30B are retracted to a position not covering the reticle pattern surface by a drive device (not shown) in accordance with a command from main controller 28. . The configuration of the reticle alignment microscope units 30A and 30B and the reticle alignment using them are disclosed in, for example, Japanese Patent Application Laid-Open No. 10-163099.

Further, the apparatus shown in FIG. 1 is provided with a position detecting device 70 described later.

The control system is mainly constituted by a main controller 26 in FIG. Main controller 26 controls the synchronous movement of reticle R and wafer W, exposure timing by a shutter (not shown), and the like so that the exposure operation is performed properly. In addition, the main controller 26 calculates the amount of change in the imaging characteristic of the projection optical system PL and corrects the entire apparatus including the imaging characteristic correction controller 47 in order to correct the imaging state.

In the present embodiment, the wafer stage 5
In order to directly measure the imaging characteristics of the projection optical system PL, the projection optical system P of the measurement mark formed on the reticle R
A photoelectric sensor unit 90 that photoelectrically detects a projected image via L is provided.

According to the photoelectric sensor unit 90, when detecting the projected image of the measurement mark formed on the reticle R via the projection optical system PL, the illumination light IL transmitted through the projection optical system PL is detected. The photoelectric conversion is performed, and the light amount signal P corresponding to the received light amount is output to the main control device 26.

The projection of the present embodiment configured as described above
In the exposure apparatus 100, as shown in FIG.
Longitudinal direction perpendicular to the scanning direction of R (Y-axis direction)
In a rectangular (slit-shaped) illumination area IAR
The reticle R is illuminated, and the reticle R
Speed V_RIs scanned. Illumination area IAR
(The center is almost coincident with the optical axis AX) through the projection optical system PL.
Is projected on the wafer W and is conjugate to the illumination area IAR.
A projection area in the form of a dot, that is, an exposure area IA is formed.
You. The wafer W has an inverted imaging relationship with the reticle R.
The wafer W has a speed V _RDirection (+ Y direction)
V) in synchronism with reticle R_WIs scanned by
The entire surface of the shot area SA on the wafer W can be exposed.
You. Scanning speed ratio V _W/ V_RIs exactly the contraction of the projection optical system PL.
It is designed for small magnification, and putter of reticle R
Pattern of the shot area SA on the wafer W
It is accurately reduced-transferred onto the top. Longitudinal direction of illumination area IAR
The width of the pattern on the reticle R is fixed by the fixed blind.
Wider than the open area PA and larger than the maximum width of the light shielding area ST.
The reticle R is set to be narrow (scan)
The entire pattern area PA is illuminated.
It has become.

In such an exposure, the main controller 26 drives the lens elements 40a and 40b in the optical axis AX direction or the tilt direction via the imaging characteristic correction controller 47, for example, for the projection magnification, the field curvature, and the symmetric distortion. By correcting the components and adjusting the internal pressure of the sealed chamber 49, for example, magnification, coma aberration, and field curvature are corrected.
However, the aberration of the projection optical system PL cannot be completely corrected only by controlling the imaging characteristics of the projection optical system PL.
For example, random aberration cannot be corrected by the above-described correction method. Therefore, the projection exposure apparatus 10 of the present embodiment
In the case of 0, an aberration correction plate 16 mounted on a plate stage PS driven in-plane to XY by a plate driving device (not shown) is further provided, and even random aberration is corrected.

Hereinafter, the manufacture of the aberration correction plate 16 and the pattern transfer by the scanning exposure apparatus 100 of this embodiment will be described with reference to FIG.
This will be described with reference to FIGS.

First, in step 101 of FIG. 3, the Fresnel zone plate FZP2 and reflection films REF1 to REF4 (hereinafter referred to as “reflection film REF” as appropriate) which have substantially the same shape as each other and are located at the same position as a second mark described later. A dummy plate 16D, which is a flat glass plate, and a stock plate on which are formed (collectively referred to as “see FIGS. 4 and 5B”) are manufactured.

Next, at step 103, the reticle R for aberration measurement is loaded on the reticle stage RS by a reticle loader (not shown). The dummy plate 16D is mounted on the plate stage PS and inserted between the reticle R and the projection optical system PL. The loaded reticle R is formed with a Fresnel zone plate FZP1 (see FIGS. 4 and 5A) as a first mark described later, and a dummy plate 16D is formed as a second mark described later. Fresnel zone plate FZ
A reflection film REF formed around P2 and each Fresnel zone plate FZP2 is formed.

Subsequently, main controller 26 controls wafer driving device 54 via stage control system 58 to drive wafer stage 50, and moves reference mark plate FM to a predetermined position immediately below projection optical system PL. At the same time, the reticle alignment microscopes 30A and 30B are driven so that the image of the pair of reticle marks and the reticle R on the fiducial mark plate FM.
The upper reticle alignment mark is moved to a position where it can be observed at the same time. The main controller 26 controls the position of the image of the pair of reticle marks and the position of the reticle alignment mark on the reticle R to the highest degree.
Drives the reticle stage RS to perform reticle positioning, that is, reticle alignment. Regarding such reticle alignment, see, for example,
No. 63099 discloses this in detail.

Next, in step 105, the positioning between the dummy plate 16D and the reticle R is performed. As shown in FIG. 4, the reticle R includes two Fresnel zone plates FZP1 outside the pattern area PA.
And the dummy plate 16D has
Illumination light IL that has passed through pattern area PA on reticle R
Outside the region PA ′ through which the two pass through, two Fresnel zone plates FZP2 and FZP2 formed corresponding to each Fresnel zone plate FZP1
A reflection film REF formed around P2 is formed. That is, one Fresnel zone plate FZP1
And one Fresnel zone plate FZP2 corresponding to this Fresnel zone plate FZP1 in the Z-axis direction.
Are paired to form two Fresnel zone plate pairs.

Here, the Fresnel zone plate FZP1
As shown in FIG. 5 (A), four linear Fresnel zone plates FZP formed in a square quadrilateral,
And a _{1 1, FZP1 2, FZP1 3} , and FZP1 _4. These Fresnel zone plates FZP1 ₁
～FZP1 ₄ is to have the same focal length of the lens capability, fringe spacing is reduced with increasing distance from the center of the Fresnel zone plate FZP1. Incidentally, the focal length of each Fresnel zone plate _{FZP1 1, FZP1 2, FZP1 3} , and FZP1 ₄ lenses capacity is set to be twice the Z-direction distance between the upper surface of the lower surface of the reticle R and the dummy plate 16D ing. Then, when the parallel light is irradiated to the Fresnel zone plate FZP1 is a Fresnel zone plate FZP1 _1, FZP1 ₃ is Y
The parallel image to the axis is formed on the focal plane, also, Fresnel zone plates FZP1 _2, FZP1 ₄ is formed on the focal plane parallel image of the X-axis.

The Fresnel zone plate FZP2
Is a Fresnel zone plate formed concentrically as shown in FIG. 5 (B). As the distance from the center of the Fresnel zone plate FZP2 increases, the stripe interval decreases. The focal length of the lens capability of the Fresnel zone plate FZP2 is set to be the same as the distance between the lower surface of the reticle R and the upper surface of the dummy plate 16D in the Z direction. And Fresnel zone plate FZ
When parallel light is applied to P2, a point image is formed on the focal plane.

Subsequently, the position detector 70 detects the XY two-dimensional position of the Fresnel zone plate FZP2 with respect to the Fresnel zone plate FZP1 in each Fresnel zone plate pair, thereby detecting the position of the dummy plate 16D with respect to the aligned reticle R. .

As shown in FIG. 6, the position detecting device 70 includes a light source 71, lenses 72 ₁ , 72 ₂ and 72 ₃ , a half mirror 73, a parallel glass plate 74, a collimator 75, lenses 76 ₁ and 76 ₂ , The imaging device 79 includes a mirror 77, a light receiving element 78, and a light receiving surface 79S as an observation surface.

Here, as the light source 71, a laser diode can be used.
For example, a PIN photodiode can be used. Further, as the imaging device 79, a solid-state imaging device including a charge-coupled light receiving element (CCD) can be used.

[0052] In the position detecting device 70, light source 71 according to an instruction from the main control unit 26 emits light, the inspection light as the first test light and the second inspection light becomes a collimated through the lens 72 _1, the after the parallel light flux is sequentially passed through the half mirror 73 and the lens 72 _2, enters the half mirror 77 via the parallel glass plate 74. Here, the lens 72 ₁ and the lens 72 by the inclination adjustment of the parallel glass plate 74 with respect to the optical axis of the optical system consisting of ₂ which, parallel glass plate 74
The lateral shift amount between the optical axes of the inspection light beam before and after the passage can be adjusted.

The inspection light reflected by the half mirror 77 is
After passing through the lens 76 ₁ , it becomes a parallel light flux again, and is irradiated on the reticle R from vertically above. As a result of irradiating the reticle R, the inspection light reflected by the reticle R
7, and passes through the parallel glass plate 74, and a lens 72 _2,
The light enters the half mirror 73. And half mirror 7
The light reflected by ₃ passes through the lens 723 and is guided to the collimator 75, and the light passing through the slit of the collimator 75 is detected by the light receiving element 78. The detection result by the light receiving element 78 is supplied to the main controller 26.

Here, the amount of light received by the light receiving element 78 is
It depends on the angle of incidence of the inspection light on the reticle R. Therefore, the main controller 26 monitors the amount of light received by the light receiving element 78 and controls the rotation of the parallel glass plate 74,
The angle of incidence of the inspection light on the reticle R is set to a desired angle, for example, 0
° (ie, normal incidence).

On the other hand, a part of the inspection light transmitted through the reticle R is applied to the Fresnel zone plate FZP1 formed on the lower surface of the reticle R, and
A part of the inspection light that has passed through the portion near the center of No. 1 where no stripe mark exists does not fall on the Fresnel zone plate FZP2.

As a result, the Fresnel zone plate FZP
Fresnel zone plate FZP1 ₁ ~FZ that make up the 1
P1 ₄ is irradiated to the inspection light transmitted through refraction, respectively reflected by the reflective film REF1~REF4 formed on the dummy plate 16D, the lower surface of the reticle R, cross-shaped image shown in Figure 7 as the first inspection image Form IM1. On the other hand, the inspection light irradiated to the Fresnel zone plate FZP2 and reflected and refracted forms a point image IM2 shown in FIG. 7 as a second inspection image on the lower surface of the reticle R. here,
The positional relationship between the image IM1 and the image IM2, specifically, the image IM1
Of the image IM2 reflects the positional relationship between the reticle R and the dummy plate 16D.

As described above, the inspection light having the images IM1 and IM2 formed on the lower surface of the reticle R passes through the reticle R, and then passes through the lens 76 ₁ , the half mirror 77 and the lens 76 ₂
Through the light-receiving surface 79S of the solid-state imaging device 79,
The images IM1 and IM2 on the lower surface of the reticle R are re-imaged. The re-formed image is captured by the imaging device 79, and the imaging result is supplied to the main controller 26.

The main controller 26 extracts the center position of the cross-shaped intersection of the cross-shaped image IM1 and the center position of the point-shaped image IM2 from the supplied data of the imaging result, and obtains their positional relationship. From this result, main controller 26 determines the positional relationship between reticle R and dummy plate 16D for one Fresnel zone plate pair.

Next, the positional relationship between the reticle R and the dummy plate 16D with respect to another pair of Fresnel zone plates is determined in the same manner as described above.

Based on the positional relationship measured for each of the two Fresnel zone plate pairs, main controller 26 determines whether the reticle R and the dummy plate 16D
Find a two-dimensional positional relationship. In other words, for both Fresnel zone plate pairs, when the center position of the cross-point intersection of the cross-shaped image IM1 and the center position of the point image IM2 match, it is determined that the reticle R and the dummy plate 16D are correctly aligned. Is determined. When the center position of the cross-shaped point of the cross image IM1 and the center position of the point image IM2 of at least one Fresnel zone plate pair are shifted, it is determined that the reticle R and the dummy plate 16D are shifted. The two-dimensional shift amount between the reticle R and the dummy plate 16D is determined from the shift amount between the center position of the cross-shaped intersection of the cross-shaped image IM1 and the center position of the point image IM2 for each Fresnel zone plate pair. When it is determined that the state is shifted, the main control device 26 determines, based on the measured amount of shift,
While monitoring the shift amount, the dummy plate 16D is driven on the XY plane via the plate driving device, and the reticle R and the dummy plate 16D are correctly positioned. Thereby, the reticle R and the dummy plate 16D are two-dimensionally aligned with high accuracy. When the center position of the cross-shaped image IM1 and the center position of the point-shaped image IM2 cannot be completely matched with each other due to a manufacturing error or the like, the position is set so as to minimize the amount of displacement. Perform alignment.

In the Fresnel zone plate pair, even if the Fresnel zone plate FZP1 and the Fresnel zone plate FZP2 are not two-dimensionally displaced, the angle of incidence of the inspection light on the reticle R deviates from 0 °. In this case, the center position of the cross point of the cross image IM1 and the center position of the point image IM2 are observed to be shifted. This is shown in FIG. In other words, the deviation of the incident angle of the inspection light on the reticle R and the positional deviation of the dummy plate 16D with respect to the reticle R cannot be distinguished. But,
As described above, as a result of irradiating the reticle R, the main controller 26 monitors the amount of light received by the light receiving element 78 among the inspection light reflected by the reticle R, and based on the monitoring result, the main controller 26 By controlling the rotation of the parallel glass plate 74 to control the incident angle of the inspection light on the reticle R to 0 °, the positional relationship between the reticle R and the dummy plate 16D can be accurately detected two-dimensionally. I can do it.

By performing the positioning using the above-described optical method, the positioning accuracy can be improved by one digit or more as compared with the case where the positioning is performed only by the mechanical method.

Returning to FIG. 3, next, at step 107, as shown in FIG. 9A, the measurement pattern formed on the reticle R is sequentially passed through the dummy plate 16D and the projection optical system PL. , Photoelectric sensor unit 90
And aberration is measured. At this time, the pattern formed on the reticle R is, for example, a lattice point pattern R (i, j) (i = 1 to 3, j = 1 to 1) as shown in FIG.
Use 3).

More specifically, main controller 26 determines the projection position Q (i, j) of each reticle pattern R (i, j) through stage control system 58 and wafer driving device 54, Is driven based on the light amount signal P from the photoelectric sensor unit 90 while driving in the XY plane. Then, main controller 26 measures the amount of deviation between design projection position P (i, j) and projection position Q (i, j) assuming that projection optical system PL has no aberration (FIG. 9C )reference). The X component of this shift amount is ΔX (i, j), and the Y component is ΔY (i, j). The residual aberration of the projection optical system PL is obtained from the displacement amounts (ΔX (i, j), ΔY (i, j)) thus measured.

Returning to FIG. 3, next, in step 109, based on the residual aberration measured above, the stock plate is processed by using the position of the Fresnel zone plate FZP2 formed on the stock plate as a reference to correct the aberration correction plate. 16 is manufactured. In manufacturing the aberration correction plate 16, for example, the reticle-facing surface of the stock plate is made parallel to the projection surface, and the amount of correction deviation (−ΔX (i, j), −
The shape of the opposing surface of the projection optical system PL that generates ΔY (i, j)), that is, the amount of correction deviation (−ΔX (i, j), −)
This is performed by obtaining the inclination of the opposing surface of the projection optical system PL with respect to the projection surface, which is determined by ΔY (i, j)) and the refractive index of the aberration correction plate 16, and processing the stock plate into the obtained shape.

During the manufacture of the aberration correction plate 16 in step 109, the dummy plate 16D is left on the optical path of the illumination light IL as in the case of measuring the aberration. Thus, during the manufacture of the aberration correction plate 16, assembly and adjustment of the projection optical device that can be performed in a state where minute aberration due to the projection optical system PL remains can be advanced.

Next, in step 111, the dummy plate 16D is removed from the optical path of the illumination light IL, and the manufactured aberration correction plate 16 is placed at the position where the dummy plate 16D is placed at the time of aberration measurement. In arranging the aberration correction plate 16, when determining the arrangement position of the dummy plate 16D at the time of measuring the aberration, the positioning member is fixed so that the arrangement at that position is reproduced, and the positioning member is used as a reference. It can be performed by positioning with mechanical accuracy, and the aberration can be obtained in the same manner as in the case of the Fresnel zone plate FZP1 formed on the reticle R and the dermy plate 16D, which is performed by positioning the reticle R and the dummy plate. Positioning with optical accuracy using the Fresnel zone plate FZP2 formed on the correction plate 16 can also be performed.

When the aberration correction plate 16 is thus arranged at a predetermined position on the optical path of the illumination light IL, as shown in FIG. 10, the reticle pattern R (i) shown in FIG. , J) is the design projection position P (i, j)
Becomes That is, the pattern formed on the reticle R is projected onto the wafer W in a state where the aberration is corrected and reduced.

Therefore, according to the exposure apparatus of this embodiment, highly accurate exposure can be performed.

In the above embodiment, two Fresnel zone plate pairs are used for detecting the position of the dummy plate 16D with respect to the reticle R. However, if three or more Fresnel zone plate pairs are used, the positioning accuracy is further improved. can do.

Although the position of the dummy plate 16D with respect to the reticle R is detected in the above embodiment, the position of the dummy plate 16D with respect to the lens barrel of the projection optical system PL may be detected. In this case, a Fresnel zone plate is formed on the upper surface of the lens barrel of the projection optical system PL. Further, both the position of the dummy plate 16D with respect to the reticle R and the position of the dummy plate 16D with respect to the lens barrel of the projection optical system PL may be detected.

In the above embodiment, the Fresnel zone plate for forming a cross image on the reticle R is formed.
Although the Fresnel zone plate for forming a point image on the dummy plate 16D is formed, a Fresnel zone plate for forming a point image on the reticle R is formed, and the dummy plate 16D is formed.
A Fresnel zone plate for forming a cross-shaped image may be formed, or both Fresnel zone plates may be formed as a Fresnel zone plate for forming a cross-shaped image or a point image. Further, a Fresnel zone plate for forming another image whose position can be specified is provided by the reticle R and the dummy plate 1.
6D may be formed.

Further, in the above embodiment, the Fresnel zone plate is used as a mark for position detection, but other types of marks can be used as marks for position detection.

In the above embodiment, the aberration correction plate is disposed between the reticle and the projection optical system.
For example, it can be arranged between the projection optical system and the wafer. Further, although the aberration is corrected by the shape of the surface of the aberration correction plate on the projection optical system side, the aberration can be corrected by the shape of the opposite surface or both surfaces.

In the above embodiment, a dummy plate and a stock plate having the same material and the same shape are prepared, and the aberration is measured using the dummy plate.
The aberration correction plate was manufactured by processing the stock plate,
Even if the aberration correction plate is manufactured by processing the plate used for aberration measurement, an aberration correction plate having the same effect as the aberration correction plate in the above embodiment can be manufactured.

In the above embodiment, a so-called step-and-scan machine has been described. However, the present invention is applicable to a step-and-repeat machine, a step-and-scan machine, and a step-and-stitch machine. In addition, the present invention can be applied to a projection exposure apparatus using a projection optical system regardless of an exposure apparatus such as a wafer exposure apparatus or a liquid crystal exposure apparatus.

In the above embodiments, the projection exposure apparatus has been described. However, the present invention is applicable to a projection optical apparatus having an imaging optical system.

[0078]

As described in detail above, according to the position detecting method of the present invention, the first object is irradiated with the illumination light,
The pattern formed on the object is converted into a second image via the projection optical system.
Since the position of the optical member arranged on the optical path of the illumination light in the projection optical device that projects onto the object is optically detected, accurate position detection is possible. Then, by performing positioning based on the position detection result by the position detection method of the present invention, the positioning of the optical member is performed with an accuracy improved by about one digit or more compared to the case of performing mechanical positioning, for example. be able to.

According to the position detecting device of the present invention, the position of the optical member is detected by using the position detecting method of the present invention, so that the position of the optical member can be detected with high accuracy.

Further, according to the method of manufacturing an aberration correcting member of the present invention, the relative position of the optical member disposed on the optical path of the illumination light with respect to the first object is detected by the position detecting method of the present invention, and the optical member and the optical member are detected. Since the optical member or an optical member substantially the same as the first member or the optical member is machined based on the aberration measurement result under a highly accurate positional relationship with the lens barrel of the projection optical system, a highly accurate aberration correction member is manufactured. can do.

According to the projection optical apparatus of the present invention, the aberration of the projection optical system is corrected by the high-precision aberration correcting member manufactured by the method of manufacturing the aberration correcting member of the present invention. The distortion of the projected image to be projected can be reduced, and the pattern formed on the first object can be accurately projected on the second object.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a projection exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a view for explaining the principle of scanning exposure of the apparatus of FIG. 1;

FIG. 3 is a flowchart for explaining an operation from manufacturing of an aberration correction plate to execution of exposure.

FIG. 4 is a diagram for explaining a positional relationship between a reticle and a dummy plate when measuring aberration.

FIG. 5 is a view for explaining a Fresnel zone plate formed on a reticle and a Fresnel zone plate formed on a dummy plate (A, B).

FIG. 6 is a diagram for explaining the configuration and operation of the position detection device.

FIG. 7 is a diagram for explaining an image formed by a Fresnel zone plate formed on a reticle and an image formed by a Fresnel zone plate formed on a dummy plate.

FIG. 8 is a diagram for explaining a change in an imaging position depending on an incident angle of inspection light.

FIG. 9 is a diagram for explaining aberration measurement (A to A);
C).

FIG. 10 is a diagram for explaining a reticle pattern projection operation when an aberration correction plate is used.

[Explanation of symbols]

10 Projection exposure device (projection optical device), 16 Aberration correction plate (Aberration correction member), 16D Dummy plate (Optical member), 26 Main control device (Processing device), 71 Light source, 7
9S: light receiving surface (observation surface), FZP1: Fresnel zone plate (first mark), FZP2: Fresnel zone plate (second mark), IM1: image (first inspection image), I
M2: image (second inspection image), PL: projection optical system, R: reticle (first object), W: wafer (second object).

Continued on the front page F-term (reference) 2F065 BB28 CC20 EE08 FF55 GG06 JJ03 JJ18 JJ26 LL00 LL04 LL20 LL43 LL46 PP12 PP22 PP23 QQ38 5F046 BA05 CB12 CB17 CB19 CB25 CC01 CC02 CC03 CC05 CC16 CC18 DA04 CB02 FA17

Claims (7)

[Claims] 1. A projection optical apparatus for irradiating a first object with illumination light and projecting a pattern formed on the first object onto a second object via a projection optical system, disposed on an optical path of the illumination light. A position detection method for detecting the position of the optical member, wherein the relative position of the optical member with respect to at least one of the first object and a lens barrel of the projection optical system is optically detected. . 2. The method according to claim 1, wherein the position detection of the optical member is performed when measuring the aberration of the pattern image projected on the second object via the optical member and the projection optical system. The position detection method described. 3. A first inspection image formed on an observation surface by inspection light via at least one first mark formed on at least one of the first object and the lens barrel of the projection optical system; The first object and the lens barrel of the projection optical system based on the positional relationship between inspection light via at least one second mark formed on the optical member and a second inspection image formed on the observation surface. The position detecting method according to claim 1, wherein a relative position of the optical member with respect to at least one of the following is detected. 4. The apparatus according to claim 3, wherein the first mark and the second mark are Fresnel zone plates.
The position detection method according to 1. 5. A projection optical device that irradiates a first object with illumination light and projects a pattern formed on the first object onto a second object via a projection optical system, and is arranged on an optical path of the illumination light. A position detecting device for detecting a position of the optical member, wherein at least one first mark formed on at least one of the first object and a lens barrel of the projection optical system, and a mark formed on the optical member. A light source for generating inspection light for illuminating at least one second mark; a first inspection image formed on the observation surface by the light via the first mark and the light via the second mark for the observation; And a processing device for detecting a relative position of the optical member with respect to at least one of the first object and a lens barrel of the projection optical system based on a positional relationship with a second inspection image formed on a surface. apparatus. 6. An aberration correcting member used in a projection optical apparatus that irradiates a first object with illumination light and projects a pattern formed on the first object onto a second object via a projection optical system. A method, comprising: arranging an optical member on an optical path of the illumination light to optically detect a relative position of the optical member with respect to at least one of the first object and a lens barrel of the projection optical system; A first step of aligning the optical member with at least one of the first object and the lens barrel of the projection optical system based on the result; and a state in which the optical member is aligned in the first step. A second step of measuring the aberration of the projected image on the second object; processing the optical member or an optical member substantially the same as the optical member based on the measurement result in the second step to form an aberration correction member. Third to manufacture Manufacturing method of aberration correction member which includes a degree. 7. A projection optical device that irradiates a first object with illumination light and projects a pattern formed on the first object onto a second object, wherein the projection optical device is arranged on an optical path of the illumination light. Item 7. An aberration correction member manufactured by the method for manufacturing an aberration correction member according to Item 6, and a projection optical system that receives illumination light through the first object and projects the pattern on the second object. Projection optics.